Passive matrix displays are a type of electronic display. Passive matrix displays are normally driven serially (i.e., one row or column at a time). Nearly all commercially available display technologies are driven by voltages or currents imposed along their periphery that address individual pixels by their row and column positions within a matrix. The most common method of driving a matrix display is to select each row (or column) in turn while the signals to drive its pixels are imposed along the entire column (or row). In this way, the entire display is driven sequentially row by row, typically at a frequency above the human visual system's flicker fusion threshold (i.e., 24 Hz to 60 Hz). In many cases, displays are driven row-by-row because there are fewer rows than columns in the most common display aspect ratios (e.g. 4:3, 16:9, etc.).